Wound therapy device and method

ABSTRACT

A wound therapy device and method includes a skin contacting element, a reactor, and a reactor housing element. The skin contacting element is configured for covering an associated tissue site, the reactor for creating a pressure condition at the associated tissue site upon actuation thereof, and the reactor housing element for accommodating the reactor. The skin contacting element has a skin contacting side and an interface side, which is opposite the skin contacting side. The reactor housing element has a lower affixing side and an upper side, which is opposite the lower affixing side.

This application claims priority to U.S. Provisional Application Ser.No. 62/248,422 filed on Oct. 30, 2015, the entirety of which isexpressly incorporated by reference.

BACKGROUND

Negative pressure is a term used to describe a pressure that is belownormal atmospheric pressure. At room temperature and at sea level, adefined volume of air contains molecules moving in random directions,and these moving molecules exert a force that is equal to the normalatmospheric pressure of approximately 756 mmHg (about 1 bar). Negativepressure has been achieved by removing air from an area of interest, forexample at a wound site via a suction pump. Devices for the generationof topical negative pressure at the surface of a subject's skin havebeen used for many hundreds of years to treat humans. For example, thecupping technique, which relates to positioning a mouth of a rigidvessel containing hot air on a human's skin, is a well-known technique.Spring powered syringes and suction cups are other mechanical techniquesthat have been used for generating a vacuum on human tissue. In commonwith cupping, such other mechanical techniques have offered a limitedtopical negative pressure duration and little or no range of neutral topositive pressures. This is due to design constraints and that thecupping technique and other mechanical techniques are not self-containedand can hinder a user's mobility.

Known topical negative pressure devices range from cumbersome wrinklereducing suction apparatuses to wound therapies that includefluid-permeable wound cavity filling elements, covering dressings,reasonably air-tight means for sealing against the skin, and drainagetubes connecting the wound site and cavity filling element to the vacuumsource via a fluid collection canister. The mode of action of suchdevices is the application of negative pressure to the tissue site,causing an expansion of the enclosed tissue into the cavity enabled bysealing the apparatus against the skin. When the treated tissue site isa wound, exudate can be drawn from the surrounding tissue through theporous cavity filler, into the drainage tube and then into a remotecollection receptacle. A consideration of such known devices is theability of the wound cavity filler to remain sufficiently porous sothat, when compressed under negative pressure, fluid may be transportedfrom the tissue site to a drainage or aspirant tube.

To enable a more prolonged application of topical negative pressure,powered systems, which include a vacuum generation source such as apump, have been developed and many examples of such systems are usedtoday for skin treatments and restorative purposes like the temporaryremoval of wrinkles. Many of these systems, however, are not convenientfor users. Such known systems can be large, heavy, noisy, uncomfortable,and not simple for users to apply and initiate a controlled pressurecondition. Such known systems also rely on an outside power or vacuumsource to create topical negative pressure conditions.

Such tissue treatment, surgery, and other advanced technicalinterventions are becoming more common given the occurrence of both theaging population, as well as increasingly compromised patientpopulations. This trend looks set to continue. In wound care, forexample, healthcare professionals are now more likely to encounterwounds that are difficult to manage with complex healing problems.Attempts have been made to produce more simple mechanical devices ableto apply topical and negative pressure to a tissue site. It will beappreciated that such a medical device, due to its relative simplicityof design, would be expected to reduce material costs and assemblycosts. For example, attempts have been made to use a hand-pump systemfor the application of topical negative pressure at a tissue site.However, such a system fails to enable easier application by the user,discreet use, and prolonged convenient application of topical negativepressure, and, in fact, re-evacuation is often necessary. These can beserious deficiencies, particularly as many such systems are ideallyuseable for prolonged periods, such as overnight.

SUMMARY

According to one aspect, a wound therapy device includes a skincontacting element, a reactor, and a reactor housing element. The skincontacting element is configured for covering an associated tissue site,the reactor for creating a pressure condition at the associated tissuesite upon actuation thereof, and the reactor housing element foraccommodating the reactor. The skin contacting element has a skincontacting side and an interface side, which is opposite the skincontacting side. The reactor housing element has a lower affixing sideand an upper side, which is opposite the lower affixing side. Thereactor housing element is configured to be affixed to the skincontacting element after the reactor is actuated.

According to another aspect, a wound therapy device includes a skincontacting element, a reactor, a reactor housing element and an airpermeable liquid impervious membrane. The skin contacting element isconfigured for covering an associated tissue site, the reactor forcreating a pressure condition at the associated tissue site uponactuation thereof, and the reactor housing element for accommodating thereactor. The skin contacting element has a skin contacting side and aninterface side, which is opposite the skin contacting side. The reactorhousing element has a lower affixing side and an upper side, which isopposite the lower affixing side. The air permeable liquid imperviousmembrane is arranged on an exposure side of the reactor so as to beinterposed between the reactor and the skin contacting element when thereactor housing element is affixed to the skin contacting element.

According to still another aspect, a wound therapy device includes askin contacting element, a reactor and a reactor housing element. Theskin contacting element is configured for covering an associated tissuesite, the reactor for creating a pressure condition at the associatedtissue site upon actuation thereof, and the reactor housing element foraccommodating the reactor. The skin contacting element has a skincontacting side and an interface side, which is opposite the skincontacting side. The reactor housing element has a lower affixing sideand an upper side, which is opposite the lower affixing side. Thereactor housing reactor housing element is removably affixed to the skincontacting element to enable removal of the reactor housing element andreplacement of one or both of the reactor and the reactor housingelement.

According to a further aspect, a method for applying controlled pressureto a tissue site includes: covering the tissue site with a skincontacting element; affixing a reactor housing element to the skincontacting element; and actuating a reactor to create a pressurecondition at the tissue site. The skin contacting element has a skincontacting side and an interface side, which is opposite the skincontacting side. The covering of the tissue site with the skincontacting element includes the skin contacting side being arranged toface the tissue site. The reactor housing element has the reactoraccommodated therein. The reactor housing element also has a loweraffixing side and an upper side, which is opposite the lower affixingside. The affixing of the reactor housing element to the skin contactingelement occurs after the actuating of the reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic exploded perspective view of a controlled pressuredevice according to an exemplary embodiment.

FIG. 1A is a schematic exploded perspective view of a skin contactingelement according to an alternate exemplary embodiment.

FIG. 2 is a schematic cross-sectional view of the controlled pressuredevice depicted in FIG. 1.

FIG. 2A is a schematic cross-sectional view of a controlled pressuredevice similar to the one shown in FIG. 2 but according to an alternateexemplary embodiment.

FIGS. 3 and 4 schematically depict reactors according to an alternateexemplary embodiments.

FIGS. 5-7 schematically depict powered components according to alternateexemplary embodiments for use with the controlled pressure device ofFIG. 1.

FIG. 8 is a block diagram of a method for applying controlled pressureto a tissue site according to an exemplary embodiment.

DETAILED DESCRIPTION

FIG. 1 depicts a controlled pressure device 10, which can also bereferred to as a wound therapy device or a self-contained wound therapydevice, according to an exemplary embodiment. The wound therapy device10 includes a skin contacting element 12, a reactor housing element 14,and a reactor 16. With additional reference to FIG. 2, the wound therapydevice 10 can also include a wound contact element 18 for direct contactwith a tissue site 20, and specifically for direct contact with a woundor treatment portion 20 a at the tissue site 20. As will be described inmore detail below, the wound therapy device 10 can be positioned at thetissue site 20 to enhance tissue treatment including, but not limitedto, wound healing (e.g., healing of the wound portion 20 a), reductionof skin wrinkles, other skin maladies, etc. As will be described in moredetail below, the skin contacting element 12 is configured for coveringthe associated tissue site 20, and particularly for covering the woundportion 20 a of the tissue site 20. As used herein, the tissue site isreferred to as an associated tissue site so as to indicate that thetissue site itself (and the wound portion 20 a of the tissue site) isnot generally considered a component of the wound therapy device 10. Thereactor housing element 14 is provided for accommodating the reactor 16and the reactor 16 is provided for creating a pressure condition at theassociated tissue site 20 upon actuation thereof (i.e., actuation of thereactor 16) for acting upon the wound portion 20 a. The wound contactelement 18 is provided for directly contacting a wound portion 20 a atthe tissue site 20 (i.e., the contact element 18 is interposed betweenthe skin contact element 12 and the wound portion 20 a).

In one embodiment, the reactor housing element 14 is configured to beaffixed to the skin contacting element 12 after the reactor 16 isactuated. In the same or another embodiment, a liquid impermeable-airpermeable membrane (e.g., membrane 100) can be provided to inhibit orlimit exudate suctioned from the tissue site 20 from reaching thereactor 16. In these or a further embodiment, the skin contactingelement 12 is configured to remain in place at a tissue site when thereactor element 14 is changed, for example when the reactor 16 issufficiently used up and a new reactor 16 is desired. In these and otherembodiments, the wound therapy device 10 is self-contained in that itdoes not need to be connected to an external power and/or vacuum sourcein contrast to many prior art devices.

The skin contacting element 12 includes a skin contacting side 30 thatis adherable to a subject's skin (e.g., around the wound portion 20 a)and an interface side 32, which is opposite to the skin contacting side30. In the illustrated embodiment, the skin contacting element 12 isshown as a separate element from the reactor housing element 14. In analternative arrangement, the skin contacting element 12 can be providedas part of the reactor housing element 14, e.g., the skin contactingelement 12 can be integrally formed with the reactor housing element 14or connected with the reactor housing element 14 at the manufacturingfacility and the elements 12,14 can be together applied to the tissuesite 20. In the illustrated embodiment, the skin contacting element 12is a flexible material (e.g., a thin gas impermeable film) that allowsthe wound therapy device 10 to conform to a subject's skin disposed atand/or around the tissue site 20. The skin contacting element 12 can bemade from a thin sheet-like membrane (e.g., a thin gas impermeablefilm), for example using a roll-to-roll process.

Also in the illustrated embodiment, the skin contacting element 12includes one or more openings 34, alternatively referred to herein asskin contacting element openings, extending through the skin contactingelement 12 from the skin contacting side 30 to the interface side 32.The skin contacting element openings 34 can be arranged for positioningover the tissue site 20, and particularly over the wound portion 20 athereof, and further arranged such that the pressure condition createdby the reactor 16 is applied to the tissue site 20, and particularly tothe wound portion 20 a, through the skin contacting element openings 34.The one or more openings 34 can be used to control or limit the speed ofscavenging by the reactor 16. For example, the number of openings 34and/or the size of the openings 34 (i.e., surface area of the openings)can effectively limit the amount of air that reaches the reactor 16 andthereby control the rate of consumption by the reactor 16. In additionto controlling the pressure condition created by the reactor 16, thiscan also control the amount or rate of heat produced by the reactor 16.

Alternatively, as shown in FIG. 1A, skin contacting element 12 a can besubstituted for skin contacting element 12 and can include a singleopening 34 a extending through the skin contacting element 12 a fromskin contacting side 30 a to interface side 32 a. The opening 34 a canbe arranged for positioning at (e.g., over or around) the tissue site20. Optionally, the skin contacting element 12 a and/or the singleopening 34 a can be dimensioned to fit around the wound portion 20 a ofthe tissue site 20. In one exemplary application, the skin contactingelement 12 a can be used and left in place when desirable to change thewicking element 36 (e.g., to a fresh wicking element) and/or to changethe reactor 16.

The wound contact element 18, also referred to herein as a wound contactlayer, can be perforated or formed as an open mesh that is minimallyadherent to breached skin tissue (e.g., the wounded portion 20 a at thetissue site 20). In one embodiment, the wound contact element 18 is aloose nylon fabric or an open mesh polyurethane film (e.g., a 1 mmpolyurethane film) that is flood coated on an underside 18 a thereofwith a coating 22 that itself is minimally adherent to breached skintissue and/or can include an anti-bacterial component (e.g., silver,chlorhexidine gluconate (CHG), etc.). For example, the coating 22 can beor include silicone, nylon, etc.

The wound therapy device 10 can further include a wicking element 36. Aswill be described in more detail below, the wicking element 36 canabsorb exudate from the tissue site 20 when the pressure condition is anegative pressure condition that partially vacuums (e.g., vacuums air oroxygen) from the tissue site 20. The wicking element 36 can havesuitable liquid retention properties for absorbing an amount of exudatefrom the tissue site 20. In one embodiment, the wicking element 36 isformed of a suitable wicking material able to withstand an externalpressure of up to about 3 psi (i.e., about 0.2 bar). In the same oranother embodiment, the wicking element 36 can maintain its shape underpressure (e.g., at 0.2 bar) or can expand as it absorbs exudate. In allembodiments, the wicking element 36 can be arranged so as to beinterposed between the reactor 16 and the tissue site 20 when the woundtherapy device 10 is applied to the tissue site 20.

The location of the wicking element 36 relative to the other componentsof the wound therapy device 10 can vary. For example, the wickingelement 36 can be positioned above or below the skin contacting element12. In the embodiment shown in FIG. 2, the wicking element 36 ispositioned above the skin contacting element 12 and below the reactor14. In this embodiment, the wicking element 36 can be provided togetherwith the reactor element 14 (e.g., positioned between release layer 70and the reactor 16) or as part of the reactor 14 (e.g., betweensubstrate 80 and lower layer 86), for example. Alternatively, in theembodiment where the wicking element 36 is positioned above the skincontacting element 12, the wicking element can be provided together withthe skin contacting element 12 (e.g., between release layer 50 andinterface side 32 of the skin contacting element 12, and optionallyadhered to the interface side 32) or the wicking element 36 can beprovided as a separate element that is assembled onto the skincontacting element (e.g., the wicking element 36 could be individuallypackaged, removed from its packaging and assembled or stacked onto theinterface side 32). In the embodiment shown in FIG. 2A, the wickingelement is provided together with the skin contacting element and isinterposed between the underside 30 of the skin contacting element 12and the wound contact element 18.

The wicking element 36 can be sized relative to the one or more openings34 (or the opening 34 a of the skin contacting element 12 a). Also, thewicking element 36 can be arranged and sized such that the pressurecondition is applied to the tissue site 20, and particularly to thewound portion 20 a thereof, through or via the wicking element 36. Forexample, the wicking element 36 can be larger than the footprint areadefined by the one or more openings 34. In the alternative embodiment ofFIG. 1A, the openings 34 and the skin contacting element 12 a can besimilarly shaped to the wicking element 36 and arranged such that theskin contacting element 12 a is disposed peripherally about the wickingelement 36. For example, the wicking element 36 can be sized to providean interference fit between the wicking element and the skin contactingelement 12 a (i.e., the portions of the skin contacting element 12 aforming the opening 34 a) or can be sized so that there is no gapbetween an outer periphery of the wicking element 36 and the skincontacting element 12 a. Still further, the wicking element 36 could belarger than the opening 34 a so as to overlap or underlap the skincontacting element 12 a.

Both the skin contacting side 30 and the interface side 32 can begenerally flat or planar, though as indicated above the skin contactingelement 12 can be flexible and able to conform to the contours at thetissue site 20. In the illustrated embodiment, the interface side 32 isthe upper side of the skin contacting element 12 and the skin contactingside 30 is the lower side of the skin contacting element 12 (i.e., lowerand thus positioned more closely to the tissue site 20 than theinterface side 32). Likewise, the wound contact element 18 can have theunderside 18 a and an upper side 18 b, both of which can be flat orplanar, though both can be flexible and able to conform to the contoursat the tissue site 20.

The wound therapy device 10 can further include at least one skinadhering or sealing element (e.g., seal 40 and adhesive 42) disposed onor adjacent the skin contacting side 30 of the skin contacting element12 for adhering or sealing the skin contacting element 12 to and/oraround the tissue site 20. In the illustrated embodiment, the at leastone skin adhering or sealing element is or includes perimeter pressureseal 40, also referred to herein as a gasket, that seals the skincontacting element 12 around the tissue site 20 so the pressurecondition created by the reactor 16 is applied to the tissue site 20. Inparticular, as shown in FIG. 2, the perimeter pressure seal 40 can sealthe wound contact element 18 and the skin contacting element 12 to thetissue site 20. In addition, or in the alternative, the at least oneskin adhering or sealing element is or includes adhesive 42 adhering theskin contacting element 12 to and/or around the tissue site 20. Inparticular, as shown in FIG. 2, the adhesive 42 is provided peripherallyaround the perimeter pressure seal to adhere the skin contacting element12 to the tissue site 20.

The seal or gasket 40 can be made from a hydrogel to further promotesealing around the tissue site 20 and thereby promote the pressurecondition (e.g., topical negative pressure) at the tissue site 20. Theadhesive 42 can be a biocompatible acrylic adhesive, for example, thatis flood coated onto the skin contacting side 30 of the skin contactingelement 12. In one embodiment, the adhesive 42 is formed as a layer onthe skin contacting side 30 of the skin contacting element 12 (e.g.,flood coated thereon), the wound contact element 18 is overlaid onto theskin contact side 30 and the seal 40 is applied as a perimeter bead(e.g., a bead of hydrogel) over the adhesive 42 at the location of aperimeter edge 18 c of the wound contact element 18. The size and/orwidth of the seal 40 can vary. In alternate embodiment, not shown, theseal 40 can be provided as a plurality of seals, such as a plurality ofconcentric rings for example.

To protect and/or package the skin contacting element 12 and the woundcontact element 18 (and optionally the wicking element 36), a first skincontacting element release layer 44, also referred to herein as atear-off barrier element, can be provided with the wound therapy device10 to protect the skin contacting side 30 of the skin contacting element12, the underside 18 a of the wound contact element 18 and optionallythe wicking element 36 (i.e., when the wicking element 36 is providedtogether with the skin contacting element 12). In particular, therelease layer 44 can be disposed over the skin contacting side 30 of theskin contacting element 12 and over the wound contact element 18. Therelease layer 44 can be removable to expose the adhesive 42 and/or theperimeter pressure seal 40 provided on the skin contacting side 30 ofthe skin contacting element 12. The release layer 44 can be similar toknown release layers and includes an upper side 46 that is releasablefrom the skin contacting side 30 of the skin contacting element 12. Therelease layer 44 can also include a lower side 48 opposite the upperside 46. In one embodiment, the release layer 44 is removably secured tothe skin contacting side 30 via a polyurethane film (not shown).Optionally, no seal 40 is provided beneath the release layer 44 but islater applied after the release layer 44 is removed.

Also optionally, a second skin contacting element release layer 50, alsoreferred to herein as an interface side release layer, can be providedwith the wound therapy device 10 to protect the interface side 32 of theskin contacting element 12 and the wicking element 36. In particular,the release layer 50 can be disposed over the interface side 32 of theskin contacting element to provide the skin contacting element as afirst package component that is separate from the reactor housingelement 14 and the reactor 16, which can together be provided as asecond package component. For example, the release layer 50 can beprovided with the skin contacting element 12 and the wound contactelement 18 are separately provided and/or packaged relative the reactorhousing element 14 and the reactor 16. The release layer 50 can be likethe release layer 44. For example, the release layer 50 can be disposedover the interface side 32 of the skin contacting element. The releaselayer 50 can be removable to expose the interface side 32. Moreparticularly, the release layer 50 can include an upper side 52 and alower side 54 opposite the upper side 52 that is releasable from theinterface side 32 of the skin contacting element 12. Optionally, whenthe wicking element 36 is provided and/or packaged together with theskin contacting element 12, the release layer 50 can also protect thewicking element 36.

The reactor housing element 14 cooperates with the skin contactingelement 12 to define an enclosed volume 56 around and/or at the tissuesite 20 when the skin contacting side 30 of the skin contacting element12 is in contact with the subject's skin (i.e., adhered around and/or atthe tissue site 20, and particularly around and/or at the wound portion20 a). Accordingly, in the illustrated embodiment, the reactor housingelement 14 defines the enclosed volume 56 in which the reactor 16 isaccommodated. The reactor housing element 14 of the illustratedembodiment includes a hood or hood portion 58 and a lower peripheralsection 60. In the illustrated embodiment, the lower peripheral section60 entirely surrounds the hood 58, which is raised in relation to thelower peripheral section 60 so as to define the enclosed volume 56around and/or at the tissue site 20 when the skin contacting element 12is in contact with the subject's skin. The reactor housing element 14can be made from a material that is air impermeable or partiallyimpermeable so that air is precluded or greatly inhibited from enteringinto the enclosed volume 56 as the reactor 16 consumes one or moreselected gases within the enclosed volume 56 and thereby reducing gaspressure within the enclosed volume 56.

In alternate embodiments, the reactor housing element 14 can be madefrom materials that are at least partially impervious to particulargasses (e.g., oxygen) and at least partially pervious to other gases(e.g., carbon dioxide, nitrogen, etc.). For example, the reactor housingelement 14 can be made from a material that exhausts a higher ratio ofcertain gases relative to other gases than would occur with directcommunication to ambient. Optionally, for example, the reactor housingelement 14 can be formed of a material that is at least partially (or ismore) gas permeable for selected gasses (e.g., nitrogen or carbondioxide gas permeable) relative to other gases to exhaust or betterexhaust the selected gas from the tissue site 20 to atmosphere.

The reactor housing element 14 can also be formed without the hood 58,i.e., the reactor housing element 14 could at least initially be planaras shown in FIG. 1. Similar to the skin contacting element 12, thereactor housing element 14 can be made from a thin sheet-like membrane,for example using a roll-to-roll process. The reactor housing element 14can be made from a flexible material that is similar to or the sameflexibility as the skin contacting element 12, which allows the woundtherapy device 10 to conform to the skin around the tissue site 20. Whenthe reactor housing element 14 is affixed to the skin contacting element12, the reactor 16 is located between the reactor housing element 14 andthe skin contacting element 12. The wicking element 36, which asdescribe above can be located in one of several different locations inthe wound therapy device 10, is interposed between the reactor 16 andthe skin contacting element 12. Since the reactor housing element 14 canbe made from a flexible material, the section of the reactor housingelement 14 that is not in contact with the skin contacting element 12 israised or offset from the tissue site 20 so as to form the hood 58.

The reactor housing element 14 includes a lower affixing surface or side62 and an upper side 64, which is opposite the lower affixing side 62.As will be described in further detail below, the reactor housingelement 14 can be affixed to the interface side 32 of the skincontacting element 12 providing a substantially air-tight seal betweenthe reactor housing element 14 and the skin contacting element 12. Thiscan preclude air migration between or along an interface between thelower side 62 of the reactor housing element 14 and the interface side32 of the skin contacting element 12. In one embodiment, the reactorhousing element 14 is provided as a separate component relative to theskin contacting element 12. In another embodiment, the reactor housingelement 12 is provided already assembled with the skin contactingelement 12.

For the interface between the reactor housing element 14 and the skincontacting element 12, the wound therapy device 10 can further includeat least one reactor adhering or sealing element (e.g., perimeterpressure seal 66 and/or adhesive 68) interposed between the skincontacting element 12 and the reactor housing element 14 for adhering orsealing the reactor housing element 14 to the skin contacting element12. In one embodiment, the at least one reactor adhering or sealingelement is or includes perimeter pressure seal 66, also referred toherein as a gasket, that seals the reactor housing element 14 to theskin contacting element 12. In the same or an alternate embodiment, theat least one reactor adhering or sealing element includes adhesive 68adhering the reactor housing element 14 to the skin contacting element12. The seal 66 can be like the seal 40, including the alternateembodiment(s) described in association with the seal 40. For example,the seal 66 can be made from a hydrogel to further promote sealingbetween the skin contacting element 12 and the reactor housing element14 to thereby enhance application of the pressure condition at thetissue site 20 and the adhesive can be formed as layer on the loweraffixing side 62 of the lower peripheral section 60 of the reactorhousing element 14 with the seal 66 applied as a perimeter bead over theadhesive layer.

When the reactor housing element 14 is separately provided and/orpackaged relative to the skin contacting element, the wound therapydevice 10 can further include a reactor housing release layer 70disposed over the lower affixing side 62 of the reactor housing element14 to protect the lower affixing side 62 and over the reactor 16 toprotect the reactor 16 and/or to inhibit actuation of the reactor 16.The release layer can be the same or similar to the release layers 44,50. The release layer 70 is removable to expose the reactor 16accommodated by the reactor housing element 14 to actuate the reactor 16as will be described in more detail below. The release layer 70 caninclude an upper side 72 that is releasable from the lower affixing side62 of the reactor housing element 14 and a lower side 74 opposite theupper side 72.

The reactor 16 can be positioned in the enclosed volume 56 and can beconfigured to react with at least one selected gas (e.g., nitrogen,oxygen, carbon dioxide, etc.) found in air to consume the at least oneselected gas within the enclosed volume 56, which can reduce gaspressure within the enclosed volume 56. The reduction in gas pressurewithin the enclosed volume 56 can result in a partial vacuum beingformed in the enclosed volume 56. As such, the pressure conditioncreated by the reactor 16 upon actuation thereof can be a topicalnegative pressure applied to the tissue site 20, and particularly to thewound portion 20 a thereof (e.g., 0.2 bar negative pressure after aninitial actuation startup period). In one embodiment, the topicalnegative pressure is a partial oxygen vacuum that absorbs oxygen fromthe tissue site 20. Optionally, the pressure condition created by thereactor 16 is a negative pressure condition that removes or vacuumsoxygen from the tissue site 20 (and particularly the wound portion 20a), and removes at least one other gas (e.g., nitrogen or carbondioxide) in addition to the oxygen from the tissue site 20. This canhave the advantage of more efficiently drawing exudate from the tissuesite 20. Also, the negative pressure condition created by the reactor 16can result in the reactor 16 and thereby the entire wound therapy device10 being urged toward the tissue site 20. Also advantageous, the limitedheat from the reactor can be used to assist in healing at the tissuesite (e.g., preventing infection).

More particularly, the reactor 16 can be positioned in the enclosedvolume 56 and can be configured to react with a selected gas found inair. In one embodiment, as the reactor 16 consumes the selected gaswithin the enclosed volume 56, the gas pressure within the enclosedvolume 56 is reduced. For example, where the reactor 16 consumes oxygen,there can be an approximate 20% reduction from atmospheric pressure inthe enclosed volume 56. An example of a reactor 16 that can be used inthe wound therapy device 10 is described in US 2014/0109890 A1, which isincorporated by reference herein. US 2014/0109890 A1 describes an oxygenbased heater; however, the oxygen based heater described in US2014/0109890 A1 can be used as the reactor 16 to consume oxygen withinthe enclosed volume 56 thus producing a partial vacuum within theenclosed volume 56. In this example, the reactor 16 includes a reducingagent, a catalytic agent for reduction of oxygen such as carbon, abinding agent and a ion conducting solution or an electrolyte solution,which can be applied onto a reactor substrate 80. The reducing agent onthe reactor substrate 80 can be zinc, aluminum, or iron, for example.This can be considered a chemical pump and/or a non-electrochemical cellreactor in that no current is flowing therein.

Advantageously, the reactor 16 can be biocompatible. For example, thereactor 16 can be such that it is suitable for using in close proximityand/or contact with a subject's skin. Also for example, the reactor 16can be pH neutral. For example, the reactor 16 can have a pH that isbetween about 6 and about 8. Optionally, the reactor 16 (e.g., thereactor substrate 80 can be provided as a flexible reactor. For example,the substrate 80 can include the agents arranged or provided to increaseflexibility of the substrate (e.g., the agents could be arranged inrows). As mentioned hereinabove, the reactor 16 can include anelectrolyte solution, which can be an aqueous electrolyte solution. Thiscan advantageously facilitate maintenance of a humid environment at thetissue site 20, and particularly at the wound portion 20 a thereof. Inaddition or in the alternative, an aqueous electrolyte solution can beprovided within the reactor housing element 14 (e.g., as a gel orabsorbed into a separate sponge, not shown).

The release layer 70 on the lower side 62 of the reactor housing element14 can operate as an air-type barrier such that the selected gas (e.g.,nitrogen, oxygen, carbon dioxide, etc.) is precluded from access to thereactor 16 until after an air-tight barrier, which in the illustratedembodiment is the release layer 70, is removed from the reactor housingelement 14. Alternatively, the reactor 16 can be provided as a package,which is shown in FIG. 1 as including an upper layer 84 and a lowerlayer 86. The upper layer 84 affixes to the lower layer 86 to enclosethe reactor substrate 80 therebetween so as to provide an air-type sealso that the selected gas is precluded from access to the reactor 16. Inthis example including the package, the upper layer 84 and/or the lowerlayer 86 can operate as an air tight barrier and that removal of theupper layer 84 from the lower layer 86, or vice versa, in whole or inpart, allows the selected gas (e.g., oxygen) access to the reactor 16 sothat the selected gas can be consumed by the reactor 16.

Alternatively, at least one of the layers (the lower layer 86 in theillustrated embodiment) can include openings 88 and a seal layer 90 canbe affixed in an air-tight manner to the lower layer 86 covering theopenings 88. Removal of the seal layer 90 from the lower layer 86exposes the reactor 16 to the selected gas via the openings 88, whichallows the reactor 16 to consume the selected gas within the enclosedvolume 56. The surface area of the openings 88 can be appropriatelysized to control the flow of the selected gas through the openings 88.This can sustain the chemical reaction of the reactor 16 to thedesirable time limit for maintaining the desired pressure condition onthe tissue site 20 for a desired duration (e.g., 12 hours, 24 hours,etc.). In addition or in the alternative, the number and/or size of theopenings 88 can be selected to control or limit the rate of consumptionof the reactor thereby controlling the pressure condition created by thereactor and/or controlling the amount of heat created by the reactor. Inaddition or in the alternative, multiple seal layers 90 can be providedso that removal of one or a selected few of the seal layers (while otherseal layers are still affixed to the lower layer 86) can also beprovided to limit the flow of the selected gas toward the reactor 16.

Additionally, to further control the pressure within the enclosed volume56, the wound therapy device 10 can include a pressure release valve 92on the reactor housing element 14, and particularly on the hood 58 ofthe reactor housing element 14. The pressure release valve 92 can allowfor selected communication between the enclosed volume 56 and ambient.The pressure release valve 92 can be operated when a predeterminedpressure differential exists between the enclosed volume 56 and ambient.

In one embodiment, the wound therapy device 10 can be packaged such thatthe reactor housing element 14 and the reactor 16 are packagedseparately from the skin contacting element 12, though this is notrequired. In such an embodiment, the release layers 50 and 70 areremoved, respectively, from the skin contacting element 12 and thereactor housing element 14. Removal of the release layer 70, asindicated above, can expose the reactor 16 and thereby actuate thereactor 16. Optionally, the release layer 70 can be affixed to the lowerlayer 86 such that removal of the release layer 70 from the reactorhousing element 14 results in removal of the lower layer 86 from theupper layer 84 thereby exposing the reactor 16 to actuate the reactor16. Alternatively, the release layer 70 can be affixed to the seal layer90 such that removal of the release layer 70 from the reactor housingelement 14 results in removal of the seal layer or layers 90 from thelower layer 86, thus exposing the reactor 16 to air via the openings 88provided in the lower layer 86. After removal of the release layer 70from the reactor housing element 14, the lower side 62 of the reactorhousing element 14 can be brought into contact with the interface side32 of the skin contacting element 12 providing a substantially air-tightseal between the reactor housing element 14 and the skin contactingelement 12, such as via the seal 66 and the adhesive 68.

Additionally, the reactor housing element 14 can include a liquidimpermeable-air permeable membrane 100, also referred to herein as anair permeable liquid impervious membrane, arranged on an exposure sideof the reactor 16 (i.e., the side facing the tissue site 20) so as to beinterposed between the reactor 16 and the skin contacting element 12(e.g., when the reactor housing element 14 is affixed to the skincontacting element 12). The membrane 100 can function to inhibit orlimit exudate suctioned from the tissue site 20 from reaching thereactor 16, particularly the reactor substrate 80, thereby hindering theeffectiveness or operational capabilities of the reactor 16. The size(i.e., surface area) of the liquid impermeable-air permeable membrane100 can depend on the location of the liquid impermeable-air permeablemembrane 100 within the wound therapy device 10. If exudate from thetissue site 20 were to come in contact with the reactor substrate 80,the chemical reaction of the reactor 16 when coming in contact with theselected gas may be impaired. As such, the membrane 100 allows airflowbetween the tissue site 20 and the reactor 16 while precluding or atleast inhibiting exudate from coming in contact with the reactor 16. Byway of example, the membrane 100 can be a polytetrafluoroethylene film,such as Gore-Tex® or a similar material.

The liquid impermeable-air permeable membrane 100 can be located indifferent locations in the wound therapy device 10. In one example, theliquid impermeable-air permeable membrane 100 can be located between thereactor substrate 80 and the lower layer 86 making up the air-tightpackage for the reactor 16. So, once the lower layer 86 (or the seallayer 90) is removed, air can gain access to the reactor 16, but exudatefrom the tissue site 20 would be precluded or at least inhibited fromtraveling through the liquid impermeable-air permeable membrane 100. Inanother example, liquid impermeable-air permeable membrane 100 can belocated between the lower layer 86 (or the seal layer 90) making up theair-tight package for the reactor 16 and wicking element 36.

In an embodiment where the reactor housing element 14 and the reactor 16are packaged separately from the skin contacting element 12, the releaselayer 70 can be removed from the reactor housing element 14. Removal ofthe release layer 70 from the reactor housing element 14 can expose thereactor 16 to air by removal of the lower layer 86, the seal layer 90,or the release layer 70 may be affixed in an air-tight manner to thereactor housing element 14 so that air is precluded from access to thereactor 16 until after the release layer 70 is removed from the reactorhousing element 14. After removal of the release layer 70 from thereactor housing element 14, the lower side 62 of the reactor housingelement 14 can be affixed to the skin contacting element 12 (e.g., afterrelease layer 50 is removed from the skin contacting element 12).

In an alternate embodiment, the wound therapy device 10 can comepre-assembled with the reactor housing element 14 already affixed to theskin contacting element 12. In this embodiment, the release 70 can beexcluded and the lower layer 86, when included, can be provided to allowcommunication therethrough to the reactor 16 (e.g., the seal layer 90can be excluded). Removal of the release layer 44 can function toactuate the reactor 16.

In a further embodiment, the reactor housing element 14 and the reactor16 can be removably affixed to the skin contacting element 12 to enablereplacement of the reactor housing element 14 and the reactor 16 withoutremoving the skin contacting element 12 from the tissue site. Inaddition, the wicking element 36 can be removable from the skincontacting element 12 after the skin contacting element 12 is adhered tothe tissue site for replacement of the wicking element 36 (e.g., whenthe wicking element is saturated beyond a predetermined amount withexudate). In one example, the reactor housing element 14, the reactor 16and the wicking element 36 can be simultaneously replaced withoutreplacement of the skin contacting element 12. In another embodiment,only one or other of the reactor housing element 14 (and reactor 16) orthe wicking element 36 can be removed and replaced.

In any embodiment, the wound therapy device 10 can be designed toaccount for certain operating and/or design parameters. Such parameterscan include, for example, the maximum exudate volume to be contained bythe wound therapy device 10 (e.g., by the wicking element 36), the rateof exudate removed from the tissue site, the amount of time to reach apreferred negative pressure (e.g., 0.2 bar negative pressure), theservice time for the wound therapy device 10 (i.e., amount of timebetween bandage changes), the expected efficiency/utilization of thereducing agent of the reactor substrate 80 (e.g., zinc), the amount ofthe reducing agent (and thus the gas scavenging capacity of the device10), etc. As an example, assuming the tissue site 20 of about 10 cm×20cm and an offset of the hood 58 (or the top of the reactor housingelement 14) of about 2.5 cm from the tissue site 20 results in theenclosed volume 56 of approximately 500 mL. Assuming that the wickingelement 36 and any other solid components (e.g., the liquidimpermeable-air permeable membrane 100) within the enclosed volume 56account for 100 mL within the enclosed volume 56 (and prior to anyexudate being drawn into the enclosed volume 56) there could be 400 mLair in the enclosed volume 56. The 400 mL of air comprises about 320 mLof nitrogen and about 80 mL of oxygen at standard temperature andpressure (STP) within the enclosed volume 56 prior to the application ofa partial vacuum from the reactor 16 consuming a selected gas in the airwithin the enclosed volume 56 and prior to any exudate being sucked intothe device 10. In actual application, the size of the tissue site 20,the offset and the enclosed volume can vary and may be much smaller thanthe example above.

One gram (1 g) of zinc (Zn) has the capacity to consume about 170 mL atSTP of oxygen (O2), which is the amount of oxygen in about 850 mL (STP)of normal dry air. Although the seals 40, 66 can be provided, there canbe leakage of ambient air into the enclosed volume 56 past the seals 40,66 and can be diffusion through the reactor housing element 14 and theskin contacting element 12. For the purposes of this disclosure, bothleakage past interfaces (e.g., leakage around the seal 40) and diffusion(e.g., diffusion through the reactor housing element 14) will bereferred to as leakage. The seals 40, 66, the skin contacting element 12and reactor housing element 14 can be configured to have a maximumleakage rate of air into the enclosed volume 56 from ambient. Forexample, a maximum leakage rate of 1 mL(STP)/hour of air into theenclosed volume from ambient results in 0.2 mL(STP) of oxygen/hour.Since 1 g of zinc consumes 170 mL of oxygen (STP), 1 g of zinc providesan adequate amount of a reducing agent to result in a 20% reduction fromnormal atmospheric pressure within the enclosed volume 56 for anextended period of time, e.g., well over 72 hours. This accounts forexudate being sucked into the device 10 from the tissue site at a rateof about 0.5 mL to 1 mL per hour. As will be understood by those withordinary skill in the art, the reactor 16 may not operate to give fullutilization of a given amount of the reducing agent and so an efficiencyfactor may need to be accounted for.

In view of the foregoing, and only by way of illustrative example, thewound therapy device 10 can be configured as follows. The reactor 16 canbe configured to have a predetermined scavenging capacity (“SC”), whichrelates to the volume of the selected gas that the reactor 16 isconfigured to consume. For example, as mentioned above, 1 g of zinc willconsume about 170 mL of oxygen (STP), so the scavenging capacity wouldbe 170 mL. The enclosed volume 56 can have a determined volume (“DV)based on the area of the tissue site 20, the size of the reactor housingelement 14, the offset of the hood 58 (or the top of the reactor housingelement 14) from the tissue site 20, taking into account the wickingelement 36 in addition to the reactor 16 and any other solid componentswithin the enclosed volume 56. For example, the determined volume of 400mL was discussed above. Also, the wound therapy device 10 can beconfigured to have a maximum leakage rate (LR) for air entering theenclosed volume 56. In addition, the wound therapy device 10 can beconfigured to have a minimum wear time (“MWT”), which relates to theminimum amount of time that the wound therapy device 10 is configured tobe worn. Assuming that it is desirable to have the reactor 16 consume,or scavenge, the selected gas for the entire minimum wear time, thewound therapy device can be configured in view of the followingrelationship:SC>DV*(% of selected gas in air)+LR*(% of selected gas in air)*MWT.

The scavenging capacity can be determined to provide a relatively smallreactor 16 in relation to the reactor housing element 14 and the tissuesite 20 to be treated. The determined volume can be determined toprovide a relatively small reactor 16 and reactor housing element 14 inview the tissue site 20 to be treated. The maximum leakage rate for airentering the enclosed volume 56 can be reduced as much as is practical;however, there may be some circumstances in which a predetermined amountof leakage is desirable, for example where cycling of pressure withinthe enclosed volume 56 is desired. For example, the maximum leakage ratefor air entering the enclosed volume 56 can be less than 10 mL/hour, andpreferably less than 1 or 2 mL/hr. The minimum wear time can bedetermined based on the desired amount of time the topical negativepressure is to be applied to the tissue site 20. For example, theminimum wear time can be equal to or greater than 72 hours, equal to orgreater than 48 hours, equal to or greater than 24 hours, equal to orgreater than 12 hours, equal to or greater than 8 hours, or equal to orgreater than 4 hours. It may be desirable to include a safety factor(e.g., a multiplier on the right side of the relationship above) toaccommodate for manufacturing tolerances, differences among tissuessites and persons placing the wound therapy device 10 on the tissue site20.

As the reactor 16 consumes the selected gas found in air within theenclosed volume 56, an exothermic reaction occurs such that the reactor16 consumes the selected gas within the enclosed volume 56. The gaspressure within the enclosed volume 56 is reduced, for example, wherethe reactor 16 consumes oxygen, there can be an approximate 20%reduction from atmospheric pressure in the enclosed volume 56. Theelectrolyte chosen for the reactor 16 can be one that is able to sustaina 0.8 bar pressure (i.e., 0.2 bar negative pressure or about 150 mmHg)within the enclosed volume for up to 8 hours, preferably for up to 12hours, and in more preferably up to 24-72 hours.

Optionally, the reactor housing element 14 could also be provided with aremovable section 160 that when removed could provide access to thereactor 16. This could enable replacement of the reactor 16 independentof the reactor housing element 14. Alternatively, the removable sectioncould enable additional ambient air access to the reactor 16 or anadditional reactor located beneath the reactor housing element 14. Forexample, the removable section 160 can be affixed to the upper layer 84of the package in which the reactor substrate 80 is located. Removal ofthe removable section 160 can result in removal of at least a portion ofthe upper layer 84 thus exposing the reactor substrate 80 to ambientair, which would result in an exothermic reaction. Alternatively, anadditional reactor (not shown) could be located beneath the reactorhousing element 14 and removal of the removable section 160 can resultin removal of at least a portion of the package (similar to the packagemade up of the upper layer 84 and the lower layer 86) thus exposing theadditional reactor to ambient air.

Different types of reactors could be used to provide topical negativepressure inside the enclosed volume 56 of the wound therapy device 10.FIG. 3 depicts a reactor 216 that can be used in place of the reactor 16shown in FIG. 1. The reactor 216 can include multiple reactor substratesor multiple regions on the same reactor substrate, which are depicted asreactor elements 80 a, 80 b and 80 c each having different chemicalproperties and/or characteristics. For example, the first reactorelement 80 a can be configured to begin consuming oxygen after beingexposed to oxygen for a very short (first) period of time t1, e.g.,nearly instantaneously. The second reactor element 80 b can beconfigured to begin consuming oxygen after being exposed to oxygen for alonger (second) period of time t2, and the third reactor element 80 ccan be configured to begin consuming oxygen after being exposed tooxygen for an even longer (third) period of time. Such a configurationcan allow for a cycling of pressure in the enclosed volume 56.

In lieu of the reactor 16 made up of the reactor substrate 80, thereactor 16 may be one or any combination of electro-chemical pumps,vacuum-on-demand devices (referred to herein as VOD), electrolyzers,pressure-reducing solid state devices, oxygen absorbing iron packets, orgetters of zirconium titanium, vanadium iron, lithium, lithium metal,magnesium, calcium, lithium barium combinations, zinc-air battery,zinc-air battery components or other materials highly reactive with theselected gases, for example, nitrogen, carbon dioxide and oxygen gasesfound in wound bed environments.

FIG. 4 depicts another reactor 226 that can be used in place of thereactor 16 shown in FIG. 1. WO 2015/054040 A1, which is incorporated byreference, describes an electrochemical cell that is adapted to consumegases, i.e., air or its gaseous non-noble constituents, within anenclosure via an electrochemical reaction. This consumption of gaswithin a sealed enclosure forms a partial vacuum. The wound therapydevice 10 can include such a reactor 226 having an electrochemical cell228 that lowers the pressure within the enclosed volume 56 through anelectrochemical reaction that takes place when a voltage is applied tothe electrochemical cell 228 by a power source 230 (depictedschematically in FIG. 4). Operation of electrochemical cell 228 in thisexample can also be achieved by controlling the current supplied to theelectrochemical cell 228 by the power source 230, for example byproviding a switch 232 that can be operated by the user. The powersource 230 can be located in the enclosed volume 56 or be providedoutside the wound therapy device 10 (e.g. on the reactor housing element14). The switch 232 can be provided outside the wound therapy device 10(e.g. on the reactor housing element 14).

In an example where the reactor is a VOD device, a VOD is a solid stateelectrochemical cell, which when charged with a low current, produces ahighly reactive material that captures gases present in the atmosphereand when sealed in an air tight system can form a partial vacuum. In aVOD device, metal is deposited to grow dendrites as a voltage is appliedacross electrodes of the VOD device and lithium salt electrolyte,charging the VOD device. Similar to charging a battery, electrons aremoved from layer to layer to form metallic lithium.

In an example where the reactor is a getter, a getter, as known in theart, is a deposit of reactor material that is used for initiating andmaintaining a partial vacuum. When gas molecules strike the gettermaterial, particular gas molecules (i.e., those of the selected gas)combine with the getter chemically or by adsorption. Thus the getterremoves the selected gas from the evacuated space until the activematerial is exhausted.

A reactor having a self-regulating oxygen getter powered by zinc-airbattery technology may be used in lieu of the above-described reactor 16made up of the reactor substrate 80. Zinc-air batteries can react tocontrol or reduce the oxygen levels in sealed site and thusself-regulate a partial vacuum pressure of approximately 0.8 bars. Ifthe zinc-air battery components are configured as a working zinc-airbattery, the battery voltage will drop when the oxygen has been depletedand the desired vacuum pressure will have been achieved. This drop involtage may be used to indicate that the desired partial vacuum has beenachieved. For example, a 675 size hearing aid zinc-air battery is ratedat 620 mAh, occupies 0.5 mL volume, and weighs 1.9 g. A 675 zinc-airbattery can remove more than 150 times its volume of oxygen.

The wound therapy device 10 can also include additional poweredcomponents, which is shown as a powered component 240 that isschematically depicted in FIG. 1. Each powered component 240, which aredescribed later with reference to FIGS. 5-7, can be electricallyconnected with a power source 242 (depicted schematically in FIG. 1)which, for example, can be a zinc-air battery exposed to ambient andelectrically connected with the powered component 240. When using azinc-air battery as the power source 242, the power source 242 would belocated outside of the enclosed volume 56 or a section of the reactorhousing element 14 or the skin contacting element 12 could be removableto allow ambient air to contact the zinc-air battery.

FIG. 5 depicts a heater 250, which is one example of a powered component240 that can be used in the wound therapy device 10, electricallyconnected with the power source 242. The heater 250 can be a thin filmheater. The heater 250 can provide heat for purposes of reducing thelikelihood of infection at the tissue site 20. A switch 252 can beprovided to control power to the heater 250.

FIG. 6 depicts a first electrode 260 and a second electrode 262electrically connected with the power source 242. The electrodes areanother example of a powered component 240 that can be used in the woundtherapy device 10. The switch 252 can be provided to control power tothe electrodes 260, 262. The first electrode 260 can be positioned on afirst side of the tissue site 20 and in contact with the skin, and thesecond electrode 262 can be positioned on a second, opposite, side ofthe tissue site 20 and in contact with the skin. The electrodes 260, 262can be used to provide electrical stimulation to the tissue site 20.

FIG. 7 depicts a light source 280, which is another example of a poweredcomponent 240 that can be used in the wound therapy device 10. The lightsource 280 can include a plurality of LEDs 282 mounted on a flexiblesubstrate 284. The LEDs 282 are electrically connected with the powersource 242. The flexible substrate 284 can be placed adjacent to theskin contacting element 12, which can include larger openings 34, whichcan allow light to pass for phototherapy. Alternatively, the lightsource could be used to indicate that a partial vacuum condition existswithin the enclosed volume 56.

Optionally, the electrically powered device 240 could be a transceiver,receiver or transmitter to enable wireless communication from the woundtherapy device. Also, instead of a the powered device 240, an RFID ornon-powered indicator (both not shown) could be embedded with thereactor 14 in the reactor housing element 14.

Optionally, though not shown, the wound therapy device 10 can include anindicator that shows a state of the pressure condition created by thereactor 16. For example, one or more of the wicking element 36, thereactor 14 or the skin contacting element 12 can include a rigid portionthat protrudes or causes a raised indicator portion to be shown throughthe reactor housing element 14. When the reactor 14 creates a negativepressure condition for example, the rigid portion will protrude or showthrough the reactor housing element 14 to indicate that a partial vacuumcondition exists inside the enclosed volume 56. In one embodiment, therigid portion can be one or more beads disposed in the wicking element36 (and the wicking element 36 protrudes peripherally about the reactor140 or disposed above the reactor 16.

A method for applying wound therapy to a tissue site will now bedescribed. In particular, the method will be described in associationwith the wound therapy device 10 described hereinabove, though it is tobe appreciated that other wound therapy devices could be used. In themethod, with reference to FIG. 8, the tissue site 20 is covered with theskin contacting element 12 at S300. As already described above, the skincontacting element 12 has a skin contacting side 30 and an interfaceside 32, which is opposite the skin contacting side 30. This covering ofthe tissue site 20 with the skin contacting element 12 further includesthe skin contacting side 30 being arranged to face the tissue site 20.

At S302, the reactor 16 is actuated to create the pressure condition atthe tissue site 20. As already described herein, actuating of thereactor 16 can include creating a negative pressure condition at thetissue site 20. This can provide a suction or partial vacuum force atthe tissue site 20 wherein exudate is vacuumed or sucked away from thetissue site 20 into the wound therapy device 10. As mentioned above, theskin contacting element 12 can include the wicking element 36 thatabsorbs the exudate from the tissue site 20 when the exudate is suckedor vacuumed away from the tissue site 20. In particular, the pressurecondition can be a negative pressure condition wherein oxygen isvacuumed from the tissue site 20. Optionally, the negative pressurecondition can also vacuum at least one other gas (e.g., nitrogen, carbondioxide, etc., or any combination thereof) from the tissue site 20 otherthan oxygen.

If not already assembled, next at S304, the reactor housing element 14having the reactor 16 accommodated therein, is affixed to the skincontacting element 12. As already described herein, the reactor housingelement 14 has the lower affixing side 62 and the upper side 64, whichis opposite the lower affixing side 62. In one embodiment, the affixingof the reactor housing element 14 to the skin contacting element 12occurs after the actuating of the reactor 16.

As discussed hereinabove, the wound therapy device 10 can include themembrane 100. When so included, the method can further includeinhibiting exudate from the tissue site 20 from fluidly communicatingwith the reactor 16 as indicated at S306. In particular, the membrane100 inhibits, reduces the likelihood and/or prevents exudate from thetissue site 20 from being vacuumed through (e.g., through the wickingelement 36) and into contact with the reactor substrate 80 and thereactor pad 82.

Optionally, the method could include removal and replacement of thereactor housing element 14 and the reactor 16 together. In addition orin the alternative, the method could also include removal andreplacement of the wicking element 36. This could occur together withthe reactor housing element 14 and the reactor 16 or by itself. Forexample, the reactor housing element 14 and the reactor 16 could betemporarily unfixed from the skin contacting element 12, the wickingelement 36 replaced and then the reactor housing element 14 and thereactor 16 re-affixed to the skin contacting element 12. In theseexamples, the skin contacting element 12 can remain adhered to thetissue site 20 and avoid undesirable disruptions at the tissue site 20.Also, as described hereinabove, the reactor 16 alone or together withthe wicking element 36 could be replaced and the reactor housing element14 re-affixed to the skin contacting element 12.

In a particular embodiment, use of the wound therapy device 10 can occuras follows. The release layer 44 can be removed from the skin contactingelement 12 to expose the adhesive 42 and optionally the perimeterpressure seal 40. Alternatively, after removal of the release layer 44,the perimeter pressure seal 40 can be added to the skin contacting side30 of the skin contacting element 12. Covering the tissue site with theskin contacting element in S300 can further include adhering and/orsealing the skin contacting element 12 to and/or around the tissue site20. In particular, such adhering and/or sealing can include both sealingand adhering via the perimeter pressure seal 40 and the adhesive 42.

With the skin contacting element 12 adhered to the tissue site 20 (oraround the tissue site 20), the release layer 50 can be removed from theinterface side 32 of the skin contacting element 12 and the releaselayer 70 can be removed from the lower side 62 of the reactor housingelement 14. Removal of the release layer 70 can also include, as alreadydescribed herein, actuation of the reactor 16 accommodated by thereactor housing element 14. Removal of the release layer 70 from thereactor housing element 14 can also function to expose the adhesive 68provided on the lower side 62 of the reactor housing element 14 andoptionally the perimeter pressure seal 66. Alternatively, the perimeterpressure seal 66 can be applied or provided onto the lower side 62 ofthe reactor housing element 14 after the release layer 70 is removed.Affixing the reactor housing element 14 to the skin contacting element12 in S304 can further include adhering and/or sealing the reactorhousing element 14 to the skin contacting element 12. Specifically, suchadhering and/or sealing of the reactor housing element 14 to the skincontacting element 12 can include both sealing and adhering via theperimeter pressure seal 66 and the adhesive 68.

Optionally, the method can further include the exhausting of a gas(e.g., nitrogen, carbon dioxide, etc., or any combination thereof) fromthe reactor housing element 14 to atmosphere via the reactor housingelement 14 being at least partially gas permeable for a particular gas(e.g., at least partially carbon dioxide or nitrogen-gas permeable).

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives or varieties thereof, may bedesirably combined into many other different systems or applications.Also that various presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims.

The invention claimed is:
 1. A wound therapy device, comprising: a skincontacting element configured for covering an associated tissue site,the skin contacting element having a skin contacting side and aninterface side, which is opposite the skin contacting side; a reactorfor creating a pressure condition at the associated tissue site uponactuation thereof; and a reactor housing element for accommodating thereactor, the reactor housing element having a lower affixing side and anupper side, which is opposite the lower affixing side; and a packageincluding at least one air-tight barrier selectively removable from thepackage, wherein the reactor is positioned within the package and aselected gas found in air is precluded from access to the reactor untilafter the at least one air-tight barrier is removed from the package. 2.The wound therapy device of claim 1 wherein the reactor is configured toconsume at least one gas found in air and the reactor housing elementincludes an air permeable liquid impervious membrane arranged on anexposure side of the reactor so as to be interposed between the reactorand the skin contacting element.
 3. The wound therapy device of claim 1further comprising a release layer disposed over the skin contactingside of the skin contacting element.
 4. The wound therapy device ofclaim 1 further including: an adhesive and a gasket disposed on the skincontacting side of the skin contacting element, which is made from athin sheet-like membrane, wherein the adhesive is provided peripherallyaround to the outside of the gasket.
 5. The wound therapy device ofclaim 1, wherein the reactor is configured to consume at least one gasfound in air, and further including: an adhesive and a gasket interposedbetween the reactor housing element and the associated tissue site,wherein the adhesive is provided peripherally around to the outside ofthe gasket.
 6. The wound therapy device of claim 1, wherein the skincontacting element includes a plurality of skin contacting elementopenings each extending from the skin contacting side to the interfaceside, the plurality of skin contacting element openings arranged suchthat the pressure condition is applied to the associated tissue sitethrough the plurality of skin contacting element openings.
 7. The woundtherapy device of claim 1 further including a wicking element interposedbetween the reactor and the associated tissue site, wherein the reactorhousing is made from a thin sheet-like membrane the wicking elementmaintains its shape under pressure up to about 3 psi.
 8. The woundtherapy device of claim 7 wherein the wicking element is disposedbetween the interface side of the skin contacting element, which is madefrom a thin sheet-like membrane, and the reactor.
 9. The wound therapydevice of claim 1 further including a reactor housing release layerdisposed over the lower affixing side of the reactor housing element andover the reactor to inhibit actuation of the reactor, the reactorhousing release layer removable to expose the reactor accommodated bythe reactor housing element to actuate the reactor; and furtherincluding an interface side release layer disposed over the interfaceside of the skin contacting element to provide the skin contactingelement as a first package component and the reactor housing element andthe reactor as a second package component.
 10. The wound therapy deviceof claim 1, wherein the reactor is one or any combination of a chemicalpump, an electro-chemical pump, a vacuum-on-demand device, anelectrolyzer, a pressure-reducing solid state device, an oxygenabsorbing iron packet, a zinc-air battery, a zinc-air battery componentand a getter of zirconium titanium, vanadium iron, lithium, lithiummetal, magnesium, calcium, lithium barium combinations.
 11. The woundtherapy device of claim 1, wherein the reactor is configured having apredetermined scavenging capacity (SC) for a selected gas, wherein anenclosed volume defined by the reactor housing element in which thereactor is accommodated has a determined volume (DV), the wound therapydevice is configured to have a maximum leakage rate (LR) for airentering the enclosed volume, and the wound therapy device is configuredto a minimum wear time (MWT), which is greater than 24 hours, wherein:SC >DV*(% of selected gas in air)+LR*(% of selected gas in air)*MWT. 12.The wound therapy device of claim 11, wherein the reactor housingelement is formed of a material that is at least partially gas permeablefor selected gasses.
 13. The wound therapy device of claim 1 furtherincluding a wicking element interposed between the reactor and theassociated tissue site that is replaceable when the reactor housingelement is removed from the skin contacting element.
 14. A method forapplying controlled pressure to a tissue site, comprising: covering thetissue site with a skin contacting element, the skin contacting elementhaving a skin contacting side and an interface side, which is oppositethe skin contacting side, said covering of the tissue site with the skincontacting element includes the skin contacting side being arranged toface the tissue site; affixing a reactor housing element having areactor accommodated therein to the skin contacting element, the reactorhousing element having a lower affixing side and an upper side, which isopposite the lower affixing side; and removing an air-tight barrier froma package containing the reactor to actuate the reactor so as to createa pressure condition at the tissue site.